Conventionally, when a plurality of single photographs are photographed and a panorama photograph is formed therefrom, it is necessary to correct the photographs to be combined so as to remove image distortions. Also, when an image photographed two-dimensionally is used to measure dimensions of an object, it is necessary to correct the photographed image so as to remove image distortions.
When a three-dimensional shape of a measuring object is measured based on two images photographed, measurement points on the measuring object are found based on the principle of a stereo method. In order to perform a three-dimensional measurement, a calibration of a camera, namely interior localizations (amount of lens distortions, focal length, and principal point position) of the camera, needs to be performed beforehand. Since the three-dimensional shape of the measuring object is found using the parallax between the images photographed by the camera, the distortions due to the camera lens used in the photographing need to be corrected very precisely.
[Patent Document 1]
JP-A-Hei09-329418 (Paragraphs 0006 and 0020, and FIG. 4 and FIG. 5)
[Patent Document 2]
JP-A-Hei11-351865 (Paragraphs 0002 and 0004, and FIG. 1 and FIG. 3)